| Author | Message | ||
     Dick Perin New member Username: Dick_perin Post Number: 1 Registered: 03-2007 Rating: N/A |
Greetings. I am contemplating the purchase of KCam and MaxStepper. I am a total newbee to CNC, other than I have sent AutoCAD drawings to service bureaus and have received finished products that I have been happy with. I am a EE and would have no trouble designing a high-level driver board. My question deals with maximums in KCam and MaxStepper. I assume that there is some sort of calibrate mode where one associates stepper pulses to linear dimensions. Is there a maximum dimension for gantry/table size? Or is there a maximum "pulse count" such that as table size increases accuracy decreases? Thank you. | ||
| Stan Gray Moderator Username: Stan Post Number: 49 Registered: 01-2007 Rating: N/A |
Welcome Dick, If I have this figured right, if MaxStepper can do 16,777,215 steps per motion and your steps/inch(spi) is 10,000 then you should be able to run a line aprox. 140'. If your at 4,000 spi you could run a line aprox. 350'. The resolution of each step wouldn't matter. I hope I figured this correct. | ||
| Kelly Ullrich Moderator Username: Kellyu Post Number: 26 Registered: 02-2007 Rating: N/A |
Stan is correct. Your maximum distance traveled depends on the CNC machines transmition in conjuction with MaxStepper's limits. MaxStepper tracks the current position in steps. The maximum posistion in steps is +_16,777,215 steps. Although the position is tracked internally in steps, you will see the position displayed as inches or mm in KCam. We typically look at an axis transmition detail in steps per inch. This is the number of steps the stepper motor must receive in one direction to achieve one inch of linear movement on the axis. If you use a belt drive on the axis, the SPI formula is (motor steps per revolution) / (drive wheel circumference). A 2.4 circumference(2 x pi x R) inch drive wheel with 200 step/rev motor will have 83.333 steps per inch or SPI. If you use a direct drive threaded rod, the SPI formula is (threads per inch) * (motor steps per revolution). I use a 20 thread per inch rod and a 200 step per rev stepper motor. My SPI is 4000. Max stepper must produce 4000 pulses to move 1 inch. My maximum is 16,777,215 / 4000 or 4,194.303 inches in one command. If I used a micro-stepping driver with 10 pulses per step then my maximum distance would be 419.4 inches. That's much more than I need with my 7.5 inch gantry table. For those who are building 8 foot plasma cutters or routers it should be enough as well. Do you have any components already picked out(drives, motors or transmition parts)? | ||
| Dick Perin New member Username: Dick_perin Post Number: 2 Registered: 03-2007 Rating: N/A |
Thank you both, Stan and Kelly, for your replies. Putting it into a simple formula makes it crystal clear. A colleague that I work with is the "mechanical" department for the office. He welds (steel, aluminum, & electrical) & has an $8,000 plasma torch. He is interested in getting a milling machine. A CNC milling machine that he might be interested in is would cost about $10K or more. He mentioned for about $1,600 he could get a gantry (XY Table?) of sufficient size for what he needs to do. I presume he is looking at something with a screw drive. He would have the task of removing the knobs and linking the shafts to stepper motors of my choice (possibly through a gear box, depending on how much torque would be needed). I would do everything else-- with the help of KCam and MaxStepper. |
